Hydraulic damper

Abstract

A hydraulic damper includes a cylinder containing hydraulic liquid therein, a piston working in the cylinder and partitioning the interior of the cylinder into first and second liquid chambers, a piston rod secured to the piston and extending to the outside, and a disc valve mounted on each side of the piston for generating damping force. The disc valve exposed to the first liquid chamber comprises at least three mutually overlapping annular discs. The outer circumference of a first disc which is located contiguous to the piston is easily deflectable, and a second disc which is located contiguous to the first disc has at least one opening, one end of which is communicated permanently with the first liquid chamber. The liquid flow flowing through the opening is intercepted by the outer circumference of the first disc when the piston moves toward the second liquid chamber, and a liquid flow passing through the opening is established due to the deflection of the first disc when the piston moves toward the first liquid chamber, thereby decreasing the damping force.

What is claimed is: 
     
       1. A hydraulic damper comprising: a cylinder containing hydraulic liquid therein;   a piston working in said cylinder and partitioning the interior of said cylinder into first and second liquid chambers;   a piston rod secured to said piston and extending to the exterior of said cylinder;   a disc valve mounted on each side of said piston for generating damping forces;   said disc valve exposed to said first liquid chamber comprising at least three mutually overlapping annular discs;   the outer circumference of a first said disc which is located contiguous to said piston being easily deflectable;   a second said disc which is located contiguous to said first disc having at least one opening, one end of which is communicated permanently with said first liquid chamber;   said opening being closed by said first disc when said piston moves toward said second liquid chamber, and said opening being opened due to deflection of said first disc when said piston moves toward said first liquid chamber; and   said first disc having large and small diameter coaxial annular portions which are integrally connected by at least one radial bridge portion, whereby said large diameter annular portion can easily deflect with respect to said small diameter portion.   
     
     
       2. A hydraulic damper as claimed in claim 1, wherein the outer circumference of said first disc is guided by a fourth annular disc which is interposed between said piston and said second disc and which moves together with said second disc when said piston moves toward said second liquid chamber with said second disc being deflected in a direction to separate from said piston.